The present invention relates to an arrangement for locking a freight container to a base, particularly a trailer, with spring-loaded clamping bolts located on the base and engaging brackets on the freight container with both form and force linkage. Each of the clamping bolts is provided with a locking head and changeable from a clamping position to a release position by a rotary lifting motion with the use of a groove curve guide, with a pressure-load, spring-loaded piston which can rotate in relation to the clamping bolt. The term freight containers is intended to mean herein both containers and interchangeable platforms, i.e., containers which can be removed from the base (trailer) both in the vertical and horizontal direction.
German Pat. No. 2,312,402 shows an arrangement of the type described, which, however, is suited only for vertical placement of the freight container. The clamping bolt can be rotated via a groove curve guide which is located on the housing. This rotatability is accomplished by a suitable mounting in the pressure charged piston. This piston is axially displaceable, but not rotatable in the cylinder of the housing.
German Pat. No. 1,917,823 shows a locking arrangement for containers where the locking head, for the purpose of locking, is subjected to a pure rotary motion. Aslo with this arrangement it is not possible to fasten interchangeable platforms on base (trailers). The rotary motion of the locking head is purely mechanical, while disengagement and engagement of the clamping bolt uses a piston loaded on both sides.
U.S. Pat. No. 3,439,821 uses a locking device which operates with form linkage but not with force linkage, with the lock engaging the later openings of containers.
The freight containers must be secured to the transport vehicle in order to prevent shifting and cancellation of the initial stressing force. This applies to ships and airplanes, but especially for road vehicles, such as trucks and trailers, and other wheeled bases. The brackets on freight containers provided for this purpose have holes or recesses into which clamping bolts attachable to the trailer can be inserted and locked. The clamping bolts are tightened in the manner of screw spindles, with their locking head solidly engaging the bracket and thus holding the entire freight container on the base.
It is necessary to apply an initial stressing force to prevent noise, especially with road transports. However, there always is the danger that the initial stressing force becomes loose by shifts in the freight container and the freight container which has only form-links, makes disturbing noises during transport. This is prevented by a pressure spring used for continuous retightening of the pressure bolt.
It is therefore, an object of the present invention to avoid the disadvantages of the present state of the art and to provide an arrangement which can be used for the locking of removable freight containers on bases, particularly trailers. In addition to force linkage, there also must be form-linkage between the base and the freight container. In the loading position, the locking head of the clamping bolt must be lowered into the base so far that it does not hinder the horizontal sliding-under of an alternate container. An additional form-linked connection is necessary so that, if needed, the freight container together with the base can be transferred to suitable vehicles when the loading devices engage the freight containers.
Another object of the present invention is to provide an arrangement of the foregoing character which is simple in construction and may be economically fabricated.
A further object of the present invention is to provide an arrangement, as described, which has a substantially long operating life and may be readily and economically maintained in service.